Image by Axon

The other day my check engine light came on. I took the car in over
the weekend while I went camping. They called me and told me I had a
faulty DPFE sensor and it'd cost $400 parts+labor so I said yes. It was
the weekend and I just wanted my car back for the coming week.

Now I'm researching what this is and it's a $40 or $80 part (depending on year). Two small
hoses go into it plus an electrical plug. And according to the Ford Focus photos in the links below, it's right in the engine
bay. Nothing special. I paid the dealership $80 parts + $300 labor!

Normally when the dealership diagnoses a problem and calls me with the proposed solution I decide if I want
to do it myself or not. Most of the time I can man up no problem and fix my car myself. But since I never heard of this part I agreed to the
work. It probably took them 15 minutes to replace. That is unless it's harder
on my car than for those Focus guys in the links below. Their sensor is right up against the firewall. That's where my IAC (Idle Air Controller) resides and that was a simple bolt-on job I performed myself.

With my manual transmission the effects were especially pronounced. Once the CEL (Check Engine Light) came on, I should've known what it'd be related to:
"Drivers complaints usually include a bucking or trailer hitching condition
during shifting or initial off-idle acceleration as part of the
driveability complaint, which can be especially noticeable on manual
transmission equipped vehicles. EGR valve replacement is the recommended
service."
http://www.niehoff.com/techtips/n_sen.html